Medical assisting Administrative and clinical procedures (5e) Chapter 28 The lymphatic and immune systems

After completing chapter 28, you will be able to: List the pathways and organs of the lymphatic system and give their locations; define lymph and tell how it is circulated in the body; define the terms infection, pathogen, and antigen; list and describe the nonspecific body defense mechanisms; explain the signs and causes of inflammation.

The Lymphatic and Immune Systems

Learning Outcomes (cont.)

28.1 Describe the pathways and organs of

the lymphatic system

28.2 Compare the nonspecific and specific

body defense mechanisms

28.3 Explain how antibodies fight infection

Learning Outcomes (cont.)

28.4 Describe the four different types of

acquired immunities

28.5 Describe the causes, signs and

symptoms, and treatments of major

immune disorders

The Lymphatic System

• Network of connecting vessels

• Functions to

– Collect lymph from between cells

– Collect lipids from digestive organs

– Defend the body against pathogens

Lymphatic Pathways

• Lymphatic capillaries

– Collect fluid

– Deliver lymph to lymphatic vessels

• Lymph vessels – lymph to nodes

• Lymph nodes

– Remove pathogens

System

Lymphatic Pathways (cont.)

• Efferent lymphatic vessels lymphatic

trunks

• Lymphatic collecting ducts

– Thoracic duct

– Right lymphatic duct

• Empty into blood stream

Lymph System

The Lymphatic System (cont.)

Area Drained

by right lymphatic duct

Right lymphatic duct

Lymph nodes Lymphatic trunks

Lymphatic vessels

Left internal jugular vein Thoracic duct Left subclavian vein

Thoracic duct Cisterna chyli

Tissue Fluid and Lymph

• Interstitial fluid

– Fluid in spaces between cells

– High in nutrients, oxygen, and small proteins

– Fluid not picked up by cells  lymph

• Lymph moves by

– Squeezing action of skeletal muscles

– Squeezing action of breathing

Lymph Nodes

• Small, glandular structures

• Afferent lymphatic vessels ~ lymph to

node

• Efferent lymphatic vessels ~ lymph from

node

Lymph Nodes (cont.)

• Lymph pools in the nodes

• Cells in nodes

against pathogen

• Nodes can generate some

lymphocytes

The Thymus and Spleen

• Thymus

– Soft, bi-lobed organ located in the

mediastinum– Functions

• Same as lymph nodes

• Also produces lymphocytes

• Produces thymosin – stimulates production of lymphocytes

The Thymus and Spleen (cont.)

• Spleen

– Largest lymphatic organ

– Upper left quadrant of abdominal cavity

– Functions

• Filters blood similarly to lymph nodes

• Removes worn-out red cells

Apply Your Knowledge

What are the lymphatic collecting ducts and

what area do they drain?

ANSWER: The collecting ducts are:

Thoracic duct, which drains the left side of the head

and neck, left arm, left side of thorax, entire

abdominopelvic area, and both legs; and the right

lymphatic duct, which drains the right side of the head

and neck, right arm, and right side of the chest.

Defenses Against Disease

• Infection – presence of a pathogen in or

on the body

• Pathogen – disease-causing agent

• Innate immunity – nonspecific defenses

• Immunities – specific defenses

surround and destroy pathogens and unwanted

debris

– Swelling – Pain

Specific Defenses

• Immunities

• Antigens

– Foreign substances in the body

– On the surfaces of pathogens

• Haptens – foreign substances too small to start an immune response

Specific Defenses

• Antibodies – respond to specific antigens

• Complements – work with antibodies

• WBCs – lymphocytes and macrophages

Specific Defenses (cont.)

Two major types of lymphocytes

Both recognize antigens in the body

Specific Defenses (cont.)

• T cell activation

– Macrophage ingests and digests a pathogen

with antigens on it

– Antigens are placed on the macrophage cell

membrane next to a major histocompatibility complex (MHC)

– T cell binds to the antigen and MHC

Diagram

Specific Defenses (cont.)

• Cytotoxic T cells

• Memory T cells

• Helper T cells

– Increase antibody formation

– Memory cell formation

– B cell formation– Phagocytosis

Specific Disease (cont.)

• Natural killer (NK) cells

Apply Your Knowledge

Identify whether each item refers to T cells, B cells, or NK

cells:

_ Primarily target cancer cells

_ Respond to antigens by becoming plasma cells

_ Must be activated to respond to an antigen

_ Bind to antigens on cells and attack them directly

_ Kill on contact

_ Need macrophages and MHC for activation

_ Make antibodies against specific antigen

• Immunoglobulins

• IgA – prevents pathogens from entering

body

• IgD – thought to control B cell activity

• IgE – involved in triggering allergic

reactions

– Binds to antigens on food, bacteria, or

incompatible blood cells– Activates compliments

Antibodies (cont.)

• Actions

– Allow phagocytes to recognize and destroy

antigens– Cause antigens to clump together

– Cover the toxic portions of antigens

– Activate complements

Apply Your Knowledge

What are the possible actions that occur when

antibodies bind to antigens?

ANSWER: Possible actions include:

 They allow phagocytes to recognize and destroy

• Primary immune response

– Slow process

– Memory cells are formed

• Secondary immune response

– Quick and carried out by memory cells

– Usually prevents person from developing

disease from the antigen

Immunities (cont.)

• Naturally acquired active

immunity

– Natural exposure to antigen

– Makes antibodies and memory cells

• Artificially acquired active immunity

– Injected with pathogen

– Makes antibodies and memory

cells

Immunities (cont.)

• Naturally acquired passive immunity

– Acquired from mother

– Short-lived

• Artificially acquired passive immunity

– Injected with antibodies

– Short-lived

Apply Your Knowledge

ANSWER: Immunization is an artificially acquired

immunity A person develops this immunity by being injected with a pathogen and then making antibodies and memory cells against the

pathogen

After you give an immunization to a 2-year-old,

her mother asks you why this will work to

prevent her from getting a disease What would

you tell her?

Major Immune System Disorders

Major Immune System Disorders (cont.)

Major Immune System Disorders (cont.)

Stage Description

Stage III Cancer cells have spread beyond the primary cancer site to nearby areas.

Stage IV Cancer cells have spread to other organs of the body.

Recurrent Cancer cells have reappeared after treatment.

Major Immune System Disorders (cont.)

Major Immune System Disorders (cont.)

Immune System (cont.)

Chronic fatigue

syndrome (CFS) Condition of severe tiredness not relieved by rest and not

related to other illnesses

Common Immune System Disorders (cont.)

Lymphedema Blockage of lymphatic vessels

resulting in tissue swellingMononucleosis “Mono”; highly contagious viral

infection spread through saliva of infected person

Apply Your Knowledge

Matching:

_ Immune response to a substance A CFS

_ Blockage of lymphatic vessels B SLE

_ “Butterfly” rash on face D Autoimmune

_ Severe tiredness F Mononucleosis

_ Uncontrolled growth of G Allergy

In Summary

28.1 The lymph system is composed of pathways known

as lymph vessels In addition to the lymph vessels, the organs of the lymphatic system include lymph nodes, located throughout the body; the thymus, in the mediastinum; and the spleen, located in the

LUQ

28.2 Nonspecific body defenses include species

resistance, mechanical and chemical barriers,

phagocytosis, fever, and inflammation

Specific defenses are immunities or defenses against very specific antigens created by B cells, T cells, and natural killer (NK) cells.

In Summary (cont.)

28.3 Antibodies work in the following ways: phagocytosis,

antigen clumping, covering (inactivating) toxic portions of antigens, and activating complements

Antibodies are also known as immunoglobulins

IgA prevents pathogens from entering the body;

IgD controls B cell activity;

IgE works with IgA in triggering allergic reactions;

IgG recognizes bacteria, viruses, and toxins and activates complements; and

IgM binds to antigens on food, bacteria, or incompatible blood cells IgM also activates complements

In Summary (cont.)

28.4 The four types of immune response are naturally

acquired active immunity, such as when someone becomes ill and develops immunity; artificially

acquired active immunity, as when an injection is given against a pathogen, preventing illness; naturally acquired

passive immunity, which occurs when an infant has its

mother’s immunity for a short while after birth and

through breast milk; and artificially acquired passive

immunity, which occurs after injection of antibodies such

as with an antivenom

In Summary (cont.)

28.5 Diseases and disorders of the immune system

include HIV infection, AIDS, cancer, and allergies, as

well as other autoimmune diseases, in which the body

attacks its own antigens

The signs, symptoms and treatments are as numerous and varied as the diseases

Some of the more common diseases and disorders are discussed in the Common Diseases and

Disorders of the Immune System section near the end

of this chapter

End of Chapter 28

Thought is an infection In the case of certain

thoughts, it becomes an

epidemic.

~Wallace Stevens